docs: def draw_anti_aliased_pixels(self, x, y1, y2, color):
          """ vertical anti-aliasing at y1 and y2 """
  
          y_max = max(y1, y2)
          y_max_int = int(y_max)
          alpha = y_max - y_max_int
  
          if alpha > 0.0 and alpha < 1.0 and y_max_int + 1 < self.image_height:
              current_pix = self.pixel[int(x), y_max_int + 1]
              r = int((1 - alpha) * current_pix[0] + alpha * color[0])
              g = int((1 - alpha) * current_pix[1] + alpha * color[1])
              b = int((1 - alpha) * current_pix[2] + alpha * color[2])
              self.pixel[x, y_max_int + 1] = (r, g, b)
  
          y_min = min(y1, y2)
          y_min_int = int(y_min)
          alpha = 1.0 - (y_min - y_min_int)
  
          if alpha > 0.0 and alpha < 1.0 and y_min_int - 1 >= 0:
              current_pix = self.pixel[x, y_min_int - 1]
              r = int((1 - alpha) * current_pix[0] + alpha * color[0])
              g = int((1 - alpha) * current_pix[1] + alpha * color[1])
              b = int((1 - alpha) * current_pix[2] + alpha * color[2])
              self.pixel[x, y_min_int - 1] = (r, g, b)